Method of repairing cracked metallic castings

ABSTRACT

A NON-THERMAL METHOD OF REPAIRING CRACKED METALLIC CASTINGS COMPRISING THE STEPS OF FORMING A PLURALITY OF SPACED OPENINGS LATERALLY ACROSS THE CRACK, REMOVING METAL FROM THE UPPER PORTION OF THE OPENINGS THEREBY FORMING A GROOVE INTERCONNECTING THE UPPER ENDS OF THE OPENINGS AND FORMING RIBS THEREBETWEEN, THE WALLS DEFINING THE SIDES OF THE GROOVE OF A STRAIGHT CONFIGURATION, THE OPENING DIRECTLY INTERSECTED BY THE CRACK BEING SUBSTANTIALLY OF LESS DEPTH THAN THE OPENINGS SPACED APART ON EACH SIDE THEREOF, THEN DEPOSITING A LOAD-BEARING, DEFORMABLE, NON-THERMAL BONDING METAL ELEMENT IN THE GROOVE SO THAT THE ENTIRE GROOVE AND OPENINGS ARE COMPLETELY FILLED. THE BONDING METAL IS STRENGTHENED AND THE METAL ELEMENT-CASTING WALL JOINT IS MADE PRESSURE-TIGHT BY COLD WORKING THE BONDING METAL. PREFERABLY, A PLURALITY OF OPENINGS AND GROOVES ARE FORMED ALONG THE CRACK IN THE ABOVE MANNER.

c. B. HARRIS 3,619,893

METHOD OF REPAIRING CRACKED METALLIC CASTINGS Nov. 16, 1971 Filed Sept. 8, 1969 FIG. I.

INVENTOR.

CLEON a. HARRIS BY 77 ATTOR EY United States Patent 3,619,893 METHOD OF REPAIRING CRACKED METALLIC CASTINGS Cleon B. Harris, 1732 Sherwood Forest Blvd., Baton Rouge, La. 70815 Continuation-impart of abandoned application Ser. No.

653,194, July 13, 1967. This application Sept. 8, 1969,

Ser. No. 867,106

Int. Cl. B22d 19/10 US. Cl. 29-402 3 Claims ABSTRACT OF THE DISCLOSURE A non-thermal method of repairing cracked metallic castings comprising the steps of forming a plurality of spaced openings laterally across the crack, removing metal from the upper portion of the openings thereby forming a groove interconnecting the upper ends of the openings and forming ribs therebetween, the walls defining the sides of the groove of a straight configuration, the opening directly intersected by the crack being substantially of less depth than the openings spaced apart on each side thereof, then depositing a load-bearing, deformable, non-thermal bonding metal element in the groove so that the entire groove and openings are completely filled. The bonding metal is strengthened and the metal elementcasting wall joint is made pressure-tight by cold working the bonding metal. Preferably, a plurality of openings and grooves are formed along the crack in the above manner.

BACKGROUND OF THE INVENTION This application is a continuation-in-part of my earlier filed, copending application, Ser. No. 653,194, filed July 13, 1967, and now abandoned.

Field of the invention This invention relates to new and useful improvements in methods of repairing cracked or broken metallic castings by non-thermal means.

Description of the prior art It is known that castings may be repaired by nonthermal means. Particularly, US. Pat. 2,436,078 which discloses a method of repairing cracked metallic castings by use of locking members of ductile metal such as Invar or other metal which becomes hardened simply by cold working. The disadvantage of such a method resides in its inability to provide strength in a transverse direction to the cracked thin walled sections. When stress is applied across the crack, the casting will usually refracture along the original fault. This is particularly disadvantageous when the crack lies along a thin portion of a casting. With the method, hereinafter described, the present disadvantages are overcome and the fractured casting may be repaired to substantially restore it to its original condition.

SUMMARY OF THE INVENTION I have invented a novel non-thermal method of repairing cracked metal castings comprising the steps of forming a plurality of spaced openings laterally across the crack, removing metal from the upper portion of the openings thereby forming a groove interconnecting the upper ends of the openings and forming ribs therebetween, the walls defining the sides of the groove of a straight configuration, the opening directly intersected by the crack being substantially of less depth than the openings spaced apart on each side thereof, then non-thermally depositing in the groove a load-bearing, deformable, bonding metal so that the entire groove and openings are 3,619,893 Patented Nov. 16, 1971 DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings wherein an example of the invention is shown, and wherein:

FIG. 1 is a plan view of a portion of a casting having a crack therein, illustrating the completed repair method of the present invention having the bonding metal in place in the grooves and openings.

FIG. 2 is a transverse, vertical, sectional view, taken along the line 22 of FIG. 1, and

FIG. 3 is an enlarged, partially exploded schematic perspective view of a portion of a casting showing the relationship of the groove, openings and bonding metal.

In the drawings, the numeral 11 designates a casting or other member having a fracture or crack 12 therein. In carrying out the improved method, a plurality of spaced openings 13, 13a and 14, shown filled in FIG. 2, are formed in the casting laterally across the crack 12 throughout the length thereof in any suitable manner. The openings 13, 13a and 14 extend downwardly from the surface of the casting 11 and preferably have their axes vertically-aligned with the fracture 12. It is essential that the openings do not extend entirely through the casting. The depth of the openings vary with the thickness of the casting being repaired but never extend through the casting.

The opening 14 intersected by the crack 12 is of less depth than the openings 13 and 13a extending laterally on either side thereof. This is illustrated generally in FIGS. 2 and 3. It has been found that this configuration distributes the stress outwardly along the filled groove and casting away from the fracture. With the stress so distributed, the repaired casting can withstand normal operating pressures for which the casting was originally designed.

The upper portion of the openings are next interconnected by forming a groove 18 (FIG. 3) which extends laterally across the fracture 12 and which is of a depth equal to approximately one-half the depth of the drilled out openings 13 and 13a. Naturally, this limitation is exceeded with respect to opening 14 which is the center opening and is intersected by the crack 12. The groove 18 extends downwardly approximately two-thirds the depth of opening 14.

As is shown in FIGS. 1 and 3, the groove 18 walls are relatively flat and generally define a rectangular configuration, rounded at either end. A plurality of spaced ribs extend upwardly in the groove 18 between openings 13, 13a and 14. Due to the cross-sectional contour of the groove 18, each bridge has a curved upper surface as shown in FIG. 2.

From the foregoing, it is readily apparent that although the bonding operation, per se, is performed in the usual manner, the preparation of the fracture makes it possible to obtain improved results.

The metal bonding element 15 (FIG. 3) may be preformed, as shown, or formed in place by adding bonding metal to the groove 18. In either event, the top 17 of the element 15 should be flat and, when in place, co-extensive with the surface of casting 11. The center protrusion 19 is necessarily at least one-third shorter than the other protrusions 16 and 16a. The bonding metal of element 15 is then cold-worked by a suitable instrument to cause the alloy of the bonding metal to harden. The cold-working of element 15 strengthens the element-casting juncture. When the element 15 is in place, the bonding metal should con form exactly to the shape and size of the groove 18. When element 15 is in place in casting 11, the crack 12 will generally be in bisecting relation with element 15.

It is understood that there is no limit as to the number of openings and length of each groove. The drawings depict three openings interconnected by groove 18 merely for the purpose of illustrating the present invention. In any event, element 15 would always have the same number of protrusions as there are openings interconnected by a single groove. In particular, where the fracture or crack appeared in a long thin section of a bridged-type casting, it would probably be necessary to have several openings on each side of the shallow central opening (depicted in FIGS. 2 and 3).

Any fracture, joint or seam could be bonded in accordance with the methods of the invention, although only a fracture has been shown and described.

Non-thermal method of repair is referred to in this application to specify the nature of the metal bonding element 15. Until just a few years ago, welding or brazing were the only methods available for repair. The new nonthermal methods of cold metal working have come about as a result of a recent development in iron-nickel alloys. These nickel alloys have a high ductility, as well as, the ability to develop exceedingly high physical properties when cold worked. The nickel content of the alloy varies from 30 up to about 60 percent by weight. Particular amounts depend on end use requirements, i.e., low nickel alloy being preferred for high temperature applications of repair casting. A general explanation of these alloys can be found in Rectenwald, R. L. Cold Metal Machine Repair, Plant Engineering, September 1967, pp. 138-145.

The foregoing description of the invention is explanatory thereof and various changes in the size, shape, and materials, as well as in the details of the illustrated construction may be made, within the scope of the appended claims, without departing from the spirit of the invention.

I claim:

1. A non-thermal method of repairing cracked metal castings comprising the steps of forming a plurality of equidistantly spaced openings laterally across the crack, the opening directly intersected by the crack being substantially of lesser depth than the openings spaced apart with equal distribution on opposite sides of the fracture, removing metal from and between the upper portion of the openings thereby forming a groove interconecting the upper ends of the openings and forming ribs therebetween, then non-thermally depositing a load-bearing, deformable, bonding metal so that the entire groove and openings are completely filled, and strengthening said bonding metal by cold working.

2. The method of claim 1 wherein there is provided a plurality of grooves and openings laying laterally across the crack along the length of the crack.

3. The method of claim 1 wherein the walls defining the sides of the groove are of a straight configuration and extend downwardly from the surface of the casting and has its axis vertically-aligned with the crack.

References Cited UNITED STATES PATENTS 2,278,334 3/1942 Scott 29-402 X 2,415,905 2/1947 Overton 525l4 2,436,078 2/1948 Scott 52-514 2,537,533 1/1951 Ingalls 29402 FOREIGN PATENTS 78,002 l/l951 Norway 29 402 JOHN F. CAMPBELL, Primary Examiner D. C. REILEY, Assistant Examiner US. Cl. X.R.

525l4; 29DIG, 49 

